BACKGROUND TO THE INVENTION A common problem is the maintenance in clean and pleasant-smelling condition of sanitary appliances such as toilets and urinals. In public places, where many such appliances may be installed, persons willing to undertake such work may be difficult to find and expensive to employ. In domestic situations, many people wish to avoid or at least minimize the work and unpleasantness of sanitary appliance maintenance.

At least a partial approach to this problem has been the addition to flushing water of various substances such as cleansers, disinfectants, perfumes, dyes and the like and combinations of these, so that intervals between cleaning can be lengthened. Many systems have been developed for doing this. They include, for example, items able to be placed in cisterns or bowls and which dissolve slowly to release the substances in question, and comparatively sophisticated equipment for automatically metering the substances in liquid form into the water supply during flushing.

There is disclosed herein apparatus which increase the choices available in this area of activity and which has certain advantages. The apparatus has been developed in response to related developments of concentrated cleansing and other agents which may be in the form of gels, pastes, viscous liquids and the like, that is to say materials which are fluent, but to a lesser degree than, for example, water. Means are required for simply and reliably injecting such materials into flushing water in small quantities over lengthy periods with limited or no user maintenance or monitoring. Due to their concentrated nature, it is desirable with such materials, particularly in domestic situations, to minimize the risk of users'skin contact with them due to their aggressive nature, and the inventive apparatus is also directed to alleviating

this problem. Ease and speed of replenishing supplies of the substances used is also desirable in both domestic and"public area"situations, and to this too the invention is directed.

SUMMARY OF THE INVENTION In a first aspect, the invention provides apparatus for injecting a fluent substance into flush water of a sanitary appliance having a flush water duct connected to a bowl, said apparatus including : a receptacle external to the appliance and containing the fluent substance; a formation having a plurality of openings in a surface washed over by the flush water during flushing of the appliance; and pumping means for pumping the fluent substance from the receptacle into the formation and through said openings into the duct.

Preferably, the formation includes at least one space in fluid communication with a plurality of said openings and through which the fluent substance passes before passing through said openings. Thus, the fluent substance can be spread over the surface.

Preferably, the formation protrudes into the duct. However, diversion of a part of the flush water through a conduit within which it washes over the formation is also possible.

It is particularly preferred that at least some of said openings are at least partially within recesses in said surface. The invention is particularly suited to fluent substances which are viscous or gel-like, as opposed to free-flowing.

Such substances may be retained in the or at least some of the recesses so that after a flush washes some of the fluent substance into the flush water, more is present in the recess (es) for entry into the flush water in one or more subsequent flushes even where pumping is intermittent and/or at a low rate.

This is convenient where fluent substances with a high concentration of active ingredients are to be dispensed very slowly into a sanitary appliance to maintain it in clean or fresh-smelling condition over a long period.

Where the fluent substance to be injected is very strongly gel-like, the effect of having multiple openings is that, at least, the substance emerges into flush water in the duct as separate pieces of gel of greater surface area than if

the substance were simply injected through a single hole, thus improving mixing of the fluent substance and the flush water.

In a particularly preferred aspect, the receptacle includes a section having a cylindrical wall within which section a quantity of said fluent substance is contained, and wherein a piston is axially movable within the cylindrical section and sealing against the cylindrical wall, the apparatus including means for displacing the piston axially thereby to pump the fluent substance from the receptacle into the formation. This arrangement, too, is particularly suited where the fluent substance to be dispensed is viscous or gel-like. Moreover, it lends itself well to an arrangement in which an assembly including the receptacle and the piston is separable by a user from the conduit. Thus, replenishment of the fluent substance when required may be by means of removing and discarding that assembly and replacing it with a new one prepacked with a new supply of the fluent substance.

The means for displacing the piston may include a gas applied under pressure to a face of the piston opposite the fluent substance. Alternatively, the means for displacing the piston may include an electric motor and transmission means for converting rotary motion of a shaft of said electric motor to linear motion of the piston.

The use of an electric motor has the advantage that close control over pumping may be achieved. Thus, pumping may be intermittent, under the control of a timer. Alternatively, or additionally if required, pumping may occur in response to usage of the appliance, for example in response to at least one of: the flushing of the sanitary appliance; approaching of the appliance by an intending user; or operation of a switching means by a user.

In a further aspect, the invention provides a method of injecting a fluent substance into flush water of a sanitary appliance having a flush water duct connected to a bowl, said method including the step of pumping the fluent substance from a receptacle which is external to the appliance and which contains the fluent substance into a space in a formation having at least one recess in a surface washed over by the flush water during flushing of the

appliance and from the space into the at least one recess, so that at least some of the fluent substance in the at least one recess enters the flush water during flushing of the appliance.

In a further aspect, the invention provides apparatus for injecting a fluent substance into flush water of a sanitary appliance having a flush water duct connected to a bowl, said apparatus including : a receptacle external to the appliance and containing the fluent substance; a formation having at least one opening in a surface washed over by the flush water during flushing of the appliance ; and pumping means for pumping the fluent substance from the receptacle into the formation and through said opening into the duct. This aspect is useful where it is less important to have multiple openings to spread or break up the fluent substance or where accumulating the fluent substance in recesses is less important or even undesirable. This may apply for some fluent substances.

Preferably, said formation in use protrudes into said flush water duct.

The or at least one said opening may be in a recess on said surface if required however, in this aspect.

Preferably, said pumping means is electrically powered and operable responsively to at least one of: operation of a switching means by a user, a signal from a transducer for detecting flushing of the sanitary appliance; and a signal from a transducer for detecting an approach to the appliance by an intending user.

Preferably, an assembly including the receptacle and the piston is separable from the flush water duct and replaceable by a user. Said assembly may include said formation.

Yet further aspects of the invention will be described below. A more detailed, but non-limiting description of several preferred embodiments will now be given, by reference to the attached drawings.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS Figure 1 is a side elevation of a sanitary appliance to which apparatus according to the invention is fitted.

Figure 2 is a cross-sectional view of a flush pipe of the sanitary appliance shown in Figure 1, the view being in the same direction as Figure 1 and the section being taken centrally through the flush pipe.

Figure 3 is a cross-sectional view of a part of the apparatus shown in Figure 2.

Figure 4 is a perspective view of one component of the apparatus shown in Figure 3.

Figure 5 is a cross-sectional view taken at Station"A-A"in Figure 3.

Figure 6 is a partially-sectioned elevation of an injector unit suitable for use in the apparatus shown in Figure 2.

Figure 7 is a partially-sectioned elevation of a further injector unit suitable for use in the apparatus shown in Figure 2.

Figure 8 is a transverse cross-sectional view of a flush pipe of a sanitary appliance with apparatus as shown in Figure 2 fitted thereto.

Figure 9 is an exploded perspective view of an alternative injector unit according to the invention.

Figure 10 is a cross-sectional view of the unit shown in Figure 9, installed to a flush water duct.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring first to Figure 1, there is shown a pedestal-type toilet (water closet) 1 having a floor-mounted bowl 2 and a cistern 3 from which flushing water is supplied to the bowl 2 through a flushing water pipe 4. Flushing water contained in the cistern 3 is rapidly released into the flushing water pipe 4 when a valve (in the cistern and not shown) is operated by a user, the water flowing into the bowl 2. Only during such flushing operations does flushing water flow in the flushing water pipe 4. Between flushing operations, the pipe 4 is empty of flushing water. Secured directly to the flushing water pipe 4 is an injection system 5, including an injector unit 6 whose purpose is to contain a supply of a concentrated cleansing agent (not shown) in the form of a gel-like fluent substance and to pump the cleansing agent into the flushing water pipe 4 at a low rate. Although the exact rate of pumping will in practice be selected

to suit the fluent substance in use and the frequency of flushing of the cistern 3, in a domestic toilet installation, a discharge rate wherein 120cc of concentrated cleansing agent is discharged over a period of several months has been used. This may be compared with the much higher rate of flow of flushing water during flushing, when typically 2 to 4 litres of water may pass through the pipe 4 within a few seconds.

It is to be understood that the term"fluent substance"which has been mentioned above will be used hereinafter to describe the material to be dispensed into the flush water. Various agents may be included in the fluent substance, including surfactants for cleaning bowl surfaces, borax for removal of brown stains and scale, antibacterial enzymes, disinfectants, water softeners, colouring agents, perfume agents and the like, and several of these may be combined into one fluent substance. The fluent substance may also be a substance required to pass into a sewage collection tank of certain chemical toilets such as are used in mobile applications or portable toilets.

The use of a fluent substance containing any or all of the above agents is within the scope of the invention.

Figure 2 shows the injection system 5 mounted to the flush water pipe 4 in more detail. The injection system 5 includes a injector unit 6 which contains the fluent substance and means for pumping it out at a neck section 7, and a nipple 8 with which the injector unit 6 is threadably engaged. The nipple 8 has a screw threaded section 9 which is threadably engaged with a boss 10 formed in the flush water pipe 4. The nipple 8 bears against a washer 11 which in turn bears against the boss 10. Secured to the nipple 8 is a formation 12 which protrudes into an interior space 26 of the flush water pipe 4. The washer 11 is optional, as adequate sealing of the nipple 8 within the boss 10 can be achieved in other ways, for example if the screw threaded section 9 has a taper thread such as is known in the art.

Figure 3 shows the nipple 8 and the formation 12 in cross-section. The formation 12 has two parts: a generally cylindrical central section 13 of which a screw-threaded section 15 is threadably engaged in a recess 23 of the nipple

8, and a cylindrical sheath 14 of fine wire gauze or mesh retained captive on the section 13. The central section 13 is shown alone in Figures 4 and 5, and has an internal space 16 and three slots 17 so that fluent substance pumped into the space 16 can flow through the slots 17 into spaces 18 between the central section 13 and the sheath 14. The sheath 14 bears on circumferential ribs 19 on the section 13 and on a cylindrical section 20. The sheath 14 is held captive between a top cylindrical section 21 and a face 22 of the boss 10. A passage 24 in the nipple 8 extends from a space 25 in which the neck section 7 of the fluent substance injector unit 6 is threadably engaged.

In operation of the injection system 5, fluent substance is pumped at a constant rate (or intermittently but at a predetermined average rate) from the injector unit 6 (as described below) into the space 25 thence through the passage 24, into the space 16 and through the slots 17 into the spaces 18.

The fluent substance enters the interior 26 of the flush water pipe 4 by passing through the sheath 14. The rate of pumping of the gel-like fluent substance is chosen to be low so that the fluent substance accumulates on the cylindrical surface of the sheath 14 i. e. on individual wires (not shown) of the wire mesh forming the sheath 14 and in interstitial spaces (not shown) between those wires. To an observer, the sheath 14 is"wetted"by the fluent substance.

When flushing occurs, flush water washes over the sheath 14 and fluent substance enters the flush water, by a combination of mechanical washing away and entry of the fluent substance into solution, depending on its composition. At the end of the flush, there is normally still some fluent substance on the surface of the sheath 14 (i. e. on the wires of the mesh or in interstitial spaces therebetween), so that it remains"wetted"ready for more fluent substance to enter the flush water in the course of another flush. The effect of having several slots 17 and spaces 18 spaced apart along the central section 13 is to spread the fluent substance approximately over the surface of the sheath 14.

If the number of flushes in a given period is particularly high for a given fluent substance pumping rate, little or no fluent substance may enter the flush

water in some of those flushes, owing to the exterior of the sheath 14 ceasing to be"wetted"with fluent substance. Conversely, if the number of flushes in a period is particularly low for a given fluent substance pumping rate, some fluent substance may not be retained on the sheath 14 but pass through it to enter the interior 26 of the pipe 4, so that a larger-than-normal quantity is washed into the flush water in each one or some of those flushes. With suitable choices of the pumping rate, the wire gauge and spacing of the wire mesh of the sheath 14, a satisfactory average dosage of fluent substance may be achieved, through no more than ordinary trial and error, for a given consistency of the fluent substance. As an example, applicant has used a pumping rate of 120cc of a concentrated gel-like fluent substance per month, a sheath of 1 Omm diameter and 17 mm length and a wire mesh woven in a square pattern with approximately 20 wires per cm and the wires being of approximately 0.1- 0.2mm diameter with satisfactory results.

It will be understood that other approaches may be used to obtain a similar injecting action. For example, the sheath 14 may be formed of solid sheet material with suitably small perforations in which fluent substance can accumulate, or a formation similar to formation 12 may be made of a porous solid material so that fluent substance may accumulate in surficial pores of that material. The essential requirement in this aspect in this embodiment is that a formation such as formation 12 be provided which has the capacity to accumulate fluent substances in one or more recesses of a surface washed over by flush water during flushing so that some fluent substance at the surface, but in normal operation not all, is washed into the flush water during a given flush. Thus the word"recesses"here is intended to be interpreted very broadly, and may mean any of the above non-limiting examples i. e. interstices of a wire gauze or mesh, pores in a porous surface, holes in a sheet material, or grooves formed on a surface, or their like, depending on the particular fluent substance to be dispensed, the expected flushing frequency and the pumping rate. These factors may be matched satisfactorily to each other by no more than ordinary trial and error.

It will also be appreciated by persons skilled in the art that protrusion of the formation 12 into the interior 26 of the pipe 4 tends to enhance the processes of mechanical washing into the flush water of fluent substance and of subsequent mixing of the fluent substance and the flush water.

Figure 6 shows, partially in cross section, an injector unit 33 which is suitable for use as the injector unit 6. The injector unit 33 is substantially as shown in Australian Patent No. 652685 which describes its construction and operation in detail, and the description in the specification of that patent is explicitly incorporated here by reference. Briefly, the injector unit 33 has a container 34 including a receptacle 35 for the fluent substance 27, the receptacle 35 having a cylindrical sidewall 37, and a piston 38 sealingly bearing on the wall 37 and able to move to displace the fluent substance 27 from the receptacle 35 though an outlet 36. The container 34 is generally cylindrical in form with a longitudinal axis 29. The piston 38 is moved toward the outlet by pressurized gas 39 bearing against a face 40 of the piston 38 opposite the fluent substance 27, the gas 39 being generated by a chemical reaction initiated once the unit 33 has been installed. As described in Australian Patent No. 652685, the injector unit 33 was developed for injecting grease into machinery parts for lubrication, the receptacle 35 in that application being prepacked with the grease at the time of manufacture and the whole unit being discarded when empty. In this application, the receptacle 35 is instead prepacked with the fluent substance 27.

Control of the rate of discharge from the receptacle in injector units of the type shown in Figure 6 is by suitable choices of outlet 36 size, fluent substance 27 properties (eg viscosity) and by the use of different quantities or types of chemical reactants. Units such as the injector unit 33 can be obtained with provision for different quantities of chemical reactants to be used to achieve emptying over specified times.

Figure 7 shows, partially in cross section, another injector unit 41 which can be used as the injector unit 6 as an alternative to the injector unit 33. The injector unit 41 is in substance the same as the automatic lubricator for

supplying grease to machinery parts that is disclosed in Australian Patent Application No. 46095/97, the specification of which is herein incorporated by reference. However, in the present application, the injector unit 41 is of course filled with fluent substance rather than grease.

The injector unit 41 has a canister 42 which defines a receptacle 43 for the fluent substance 44. A piston 45 sealingly and slidingly bears on a cylindrical wall 28 of the receptacle 43 and can move towards an outlet 46 to pump fluent substance 44 therefrom. A shaft 47 is threadably engaged with the piston 45 so that when the shaft 49 is rotated the piston 45 moves lengthwise. Threadably engaged with the canister 42 is a housing 50. This contains batteries 51, an electric motor 53 and control circuitry 52 therefor, and a gearbox 54 whose gear train (not shown) is driven by the motor 53. A recessed output shaft 55 of the gearbox 54 engages a nut 56 on the shaft 47 so that operation of the motor 53 causes rotation of the shaft 47 and linear movement of the piston 45 to pump fluent substance 44 through the outlet 46.

The canister 42 and housing 50 are approximately cylindrical about a longitudinal axis 30. The control circuitry 52 includes a timer, adjustable by a user, which in use operates the motor 53 at regular intervals to achieve a desired average rate of pumping of the fluent substance 44. The operation of the injector unit 41 is more fully described in the aforementioned Australian Patent Application No. 46095/97.

As is the practice with grease lubricators of the type shown in Figure 7, the receptacle 43 of the canister 42 can for the present application be prepacked with the fluent substance 44 at the time of manufacture, and discarded when empty, the housing 50 and its contents being simply screwed on to a new canister 42.

Although embodiments of the invention have been described in which fluent substance is injected automatically at a constant or only-slowly-varying average rate, the invention has also been found useful in other situations. For example only, it may be used where injection is required responsively to every flush, or at certain times of the day only. The injector unit 41 is particularly well

adapted to such situations, as the control motor 53 may be arranged to operate when required, by connection to a user-operable switch, or to a sensor adapted to provide an electrical output when flushing occurs, such as is known in the art, or to a more sophisticated timer than one adapted only to provide regular periods of operation.

It will be appreciated that alternatives are possible to the injector units 33 and 41. For example, the injector unit 6 could be similar in its general arrangement to the injector unit 33 except for having its gas placed in it under pressure at the time of manufacture rather than generated by chemical reaction, similarly to the propellant gas in an ordinary spray can. For further example, a compressed coil spring could even be used to move the piston in an injector unit otherwise similar to the injector unit 33. (This arrangement is more difficult to provide at a low cost and in a form suitable for use by consumers, however.) The injection system 5 has been shown fitted to a boss 10 in the flush water pipe 4 as would be appropriate for a sanitary appliance 1 manufactured to be so fitted. However, as shown in Figure 8, it may also be fitted to a flush pipe 60 of an existing sanitary appliance without replacing the flush pipe 60. A hole 61 is drilled in the flush water pipe 60 and the formation 12 and part of the nipple 8 passed through the hole 61, with a washer 62 shaped to the external contour of the pipe 60 between the nipple 8 and the pipe 60 providing sealing.

The system 5 is clamped to the pipe 60 by a clamp 63 having a crossmember 64 threadably engaged with the nipple 8. Another way of fitting the injection system 5 to an existing flush water pipe such as 60 would be with a suitable adhesive/sealant.

It will be readily apparent that apparatus according to the invention may be made in many ways. Figure 9 shows a fitting 200 which combines the functions of components 8 and 13 in a single component. Component 200 is shown in cross-section in Figure 10, mounted to the boss 10 of the pipe 4 with a washer 213. Component 10 has three sections: an upper section 201 similar to component 13, a threaded central section 202 which in use is threadably

received in the boss 10, and a lower section 203. Sections 201-203 are of circular cross-section, and the cross-sectional view in Figure 10 is taken on a diametral plane. A sheath 204, similar (including in its purpose) to the sheath 14, is push-fitted onto the section 201. A fluent substance to be dispensed (not shown) can be pumped from an injector unit (such as 41) screwed into a threaded hole 205 in section 203, through a passage 206 and out through slots 207 in section 201. Spaces similar to the spaces 18 of component 13 are not included in section 201, so that there is less effective spreading of the fluent substance over the surface of the sheath 204. Of course, upper section 201 may also be formed similarly to component 13 to achieve the advantages of that component.

Arrow 208 shows the direction of flush water flow in the pipe 4. Facing upstream is a port 209 which is connected by a passage 210 to a threaded hole 211 in section 203 into which a pressure transducer (not shown) is mountable. A bung 212 is inserted into passage 210 to seal it after it is drilled.

Pressure developed at the port 209 due to flow of flush water during flushing (not shown) in the pipe 4 is detected by the pressure transducer, so that a signal from the transducer may trigger an injection of the fluent substance responsively to flushing additionally (or alternatively) to any automatic injection by the injector unit.

In a prototype, the component 200 was conveniently formed from a block of acetal plastics material.

Further disclosure of the invention is contained in the following claims.

Many variations may be made without departure from the spirit and scope of the invention.